Direct device-to-device (D2D) communications may be used in wireless networks. D2D communications may refer to wireless communication transmission exchanged directly between two or more wireless transmit/receive units (WTRUs) without the communications being routed through wireless communication infrastructure such as base stations or access points (e.g., although the wireless infrastructure may be used for configuring a D2D session and/or scheduling D2D transmissions). D2D communications may be used to provide proximity-based service (Pro-Se) among WTRUs. D2D communications may provide support for commercial, social, and public safety communications. A D2D infrastructure may provide consistency in user experience, for example including reachability and mobility aspects. D2D may provide network offloading in high traffic cells. For example, D2D may provide support for various services and/or applications when network coverage is limited or unavailable.
With respect to supporting public safety communications, there may be a need to harmonize the radio access technology across jurisdictions and lower the cost of radio-access technology to public safety (PS) officials. For example, first responders may require communications in areas that may not be under radio coverage of an LTE network. For example, a WTRU may be out of coverage in tunnels, basements, or areas where network service is disrupted due to natural disasters, terrorist attacks and the like. D2D communications may be supported for PS. For example, D2D may provide direct push-to-talk services to first responders who may be handling time sensitive emergencies.
D2D communications may be available for commercial uses, for example utility companies or the like. For example, D2D communication techniques may be used for enhancing communications in areas that may have poor coverage from network infrastructure. Commercial and social users may request D2D communications, for example, to assure the consistency of their user experience. For example, a user may request D2D communications to improve the user's reachability and/or mobility.